1. Field of the Invention
The present invention relates to a fluoroscopy.
2. Description of Related Art
As shown in FIG. 2, a fluoroscopy for digestive organs includes, for example, a table top 4, an X-ray tube device 1, an X-ray diaphragm 16, and an X-ray image detector 3 etc. The table top 4 is held by using a main column 5 vertically standing on a floor through a base 6, so as to carry a subject (not shown). The X-ray tube device 1 is held by using an arm 26 mounted on a column 2, and the column 2 is movably held in a length direction of the table top 4 by using the main column 5. The X-ray diaphragm 16 is mounted on an X-ray irradiating section of the X-ray tube device 1 and opens or closes a rectangular irradiation field. The X-ray image detector 3 is arranged on a back side of the table top 4 opposite to the X-ray tube device 1, and is movably held in the length direction of the table top 4 by using the table top 4, and includes, for example, a flat-panel-type X-ray detector or a cassette having a built-in film. Furthermore, the X-ray tube device 1 and the X-ray image detector 3 are generally configured in the following manner, that is, the X-ray tube device 1 and the X-ray image detector 3 are moved parallel to the table top 4 while maintaining a fixed position relation between each other through a mechanical combination of the parts for holding the X-ray tube device 1 and the X-ray image detector 3, or through a control motion of a control section (not shown) formed by, for example, a microcomputer as disclosed in, for example, Japanese Patent Laid-open Publication No. 2002-28155 (hereafter referred to as “Patent Document 1”).
Particularly, in the fluoroscopy for digestive organs, considering the position relation between the X-ray tube device 1 and the X-ray image detector 3, a focal point (not shown in FIG. 2) of the X-ray tube device 1 is always arranged directly above a central position of the X-ray image detector 3. Therefore, as shown in FIG. 12, when one end of the X-ray image detector 3 comes to one end of the table top 4, a focal point 1A is located directly above a detector center 3A of the X-ray image detector 3, so as to become a moving limit position of one side of the X-ray tube device 1. Here, the position is temporarily called a first moving limit position. Furthermore, in the digestive organ contrasting photography, a region of interest for the photography is not located in the vicinity of the end of the table top 4, such that a practical moving limit position of the X-ray tube device 1 is set at a suitable position of one side that is nearer to the center of the length direction of the table top 4 as compared with the first moving limit position. In addition, in FIGS. 12, 21 and 22 represent two irradiation fields having different sizes, and the irradiation fields are described in the following. In addition, the reference numerals in FIG. 12 the same as that in FIG. 2 indicate the same parts as that in FIG. 2, so that the descriptions thereof are omitted.
The fluoroscopy for digestive organs is configured in the above manner, but recently the fluoroscopy for digestive organs with the above configuration is used in a urinary organ contrasting inspection. FIG. 10 shows a situation of urinary organ contrasting photography using the fluoroscopy for digestive organs. However, a catheter is inserted into the urethra of a subject 7 from a foot side of the subject 7, such that a foot rest 17 for placing feet of the subject 7 is mounted on a foot side end of the table top 4, and thus the subject 7 is carried on the table top 4 in a manner of being close to the foot side of the table top 4. Next, when the table top 4 is rotated or the subject 7 is moved after the catheter is inserted, the body of the subject 7 bears a heavy burden, such that it is necessary to perform the photography on the original position as much as possible. As a result, in the urinary organ contrasting photography, the region of interest, for example, a bladder 7A, is often located in the vicinity of the end of the table top 4.
Therefore, in order to enable the fluoroscopy for digestive organs to be used in the urinary organ contrasting inspection, most devices expand the setting of the practical moving limit position of the X-ray tube device 1 to the first moving limit position. As a result, even if the subject 7 is carried on the table top 4 in a manner of being close to the foot side of the table top 4 as shown in FIG. 10, and the bladder 7A serving as the region of interest is located in the vicinity of the end of the table top 4, by moving the X-ray tube device 1 to the first moving limit position, and operating the X-ray diaphragm 16 to set the irradiation field to become as wide as, for example, the irradiation field 21, the photography is performed on the bladder 7A. Furthermore, when the bladder 7A is located on one side slightly closer to the center of the table top 4, the setting of the irradiation field is altered in such a way that the irradiation field 21 as shown in FIG. 12 is replaced by the slightly narrower irradiation field 22 for covering the bladder 7A, thereby alleviating the over-irradiation on the subject 7. In addition, the reference numerals in FIG. 10 the same as that in FIG. 12 indicate the same parts as that in FIG. 12, so that the descriptions thereof are omitted.